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So after a week of stable nitrogen (no NH3, NO2 and single digits NO3) I have decided to get some clean-up crew in. I have got couple of hermit crabs, few turbos, one babylonia and sand sifting starfish. Not much to look in, but hopefully the guys are going to enjoy the algae which is kicking in.

"Before any chemical experiments, check some physics." or "Before fixing things with supplements, try some water changes."

I have been somewhat concerned about my alkalinity dropping during the first week. I was looking for complicated solutions and in the end the simple one fixed it. It seems. I have done couple of 15% WC, and things are settling down nicely.

So I have gone through my first chemistry puzzle. I call it "The Vanishing Alk".

As I wrote yesterday, my Alk was coming down hard over the first week of the system life. From the initial 3.66 meq/l to 2.35 meq/l after some six days. While I noted the Ca was very high at around 600 ppm.

After reading numerous pieces of information, understanding the story of CaCO3 precipitation, I have guessed that the high Ca is precipitating in the tank (indeed there is...

I am pretty happy with it. There is a mixture of live rock and dead rock (the big one in the middle) in the tank. Aragonite sand on the bottom (1-3mm). In the sump there is deep sand of finer sand mixed...